Two significantly similar cars, no doubt about that. Still, each one has something different to offer. Having both cars powered by diesel engines and utilizing the 4-door sedan body style within the same 'Large family car' segment, the only major difference here really is their wheel drive configuration (front for the Audi and rear in the case of the BMW). The first one has a Volkswagen-engineered powertrain under the hood, a 4-cylinder, 16-valves 150hp unit, while the other one gets its power and torque from a 4-cylinder, 16-valves 150hp engine designed by BMW.

Both vehicles got tested by European New Car Assessment Programme (Euro NCAP), with the same number of safety stars gained in the process. That aside, let's consider some other aspects which affect safety. Both vehicles belong to the large family car segment, which is generally a good thing safety-wise, still it doesn't help us solve our dilemma, does it? Furthermore, taking kerb weight as an important factor into account, Audi A4 offers a marginal difference of 5% more metal.

Reliability is not the best thing to consider on the make level, but it is worth mentioning that both brands display similar results in faults and breakdowns, at least on all of the models level. That's the official data, while our visitors describe reliability of Audi, as well as BMW, with the same average rating of 4.2 out of 5. Independent research findings rank A4 as average reliability-wise, and 3 Series is more or less at the same level.We should definitely mention that owners of cars with the same powertrain as Audi A4 rank it on average as 4.6, while the one under the competitor's bonnet gets 5.0 out of 5.

BMW is a bit more agile, reaching 100km/h in 0.3 seconds less than its competitor. Still, it lacks the power to win the top speed competition, topping at 215 kilometers per hour, 5km/h less than the other car. When it comes to fuel economy things look pretty much the same for both cars, averaging around 4.3 liters of fuel per 100 kilometers (66 mpg), in combined cycle.

BMW appears just a bit more reliable, although the difference is truly marginal. The most important thing when deciding between any two vehicles should always be safety, both passive and active. In my opinion, everything taken into account, Audi A4 offers slightly better overall protection and takes the lead. From there things take a different direction, with BMW offering somewhat better performance, just enough to call it quicker. It does come at a cost though, and that's the fuel consumption... No mistake, whatever you decide here, but I'd still go for the Audi. In any case that's my personal view, built upon all the data available to me. What should decide here though is the way you feel about the two vehicles, and I hope you'll find my guidelines useful in the process. In case you have two minutes to spare I invite you to define your needs, desires and budget and see which car would be chosen by the virtual adviser™, out of 12.000+ vehicles we currently have in our database.